Liquid crystalline medium and liquid crystal display

ABSTRACT

The instant invention relates to liquid crystalline media comprising a dielectrically positive component, component A, consisting of dielectrically positive compounds, comprising one or more compounds of formula I and one or more compounds of formula II  
                 
wherein the parameters have the meaning given in the specification and to liquid crystal displays comprising these media, especially to active matrix displays.

FIELD OF THE INVENTION

The present invention relates to liquid crystalline media and to liquidcrystal displays comprising these media, especially to displaysaddressed by an active matrix and in particular to displays of theTN-type.

PROBLEM TO BE SOLVED AND STATE OF THE ART

Liquid Crystal Displays (LCDs) are widely used to display information.Electro-optical modes employed are e.g. the twisted nematic (TN)-, thesuper twisted nematic (STN)-, the optically compensated bend (OCB)- andthe electrically controlled birefringence (ECB)-mode with their variousmodifications, as well as others. Besides these modes, which all do usean electrical field, which is substantially perpendicular to thesubstrates, respectively to the liquid crystal layer, there are alsoelectro-optical modes employing an electrical field substantiallyparallel to the substrates, respectively the liquid crystal layer, likee.g. the In-Plane Switching mode (as disclosed e.g. in DE 40 00 451 andEP 0 588 568). Especially this electro-optical mode is used for LCDs formodern desk-top monitors.

The liquid crystals according to the present invention are preferablyused in TN-AM displays.

For these displays new liquid crystalline media with improved propertiesare required. Especially the birefringence (Δn) should be sufficientlyhigh. Further, the dielectric anisotropy (Δε) should be high enough toallow a reasonably low operation voltage. Preferably Δε should be higherthan 7 and very preferably be higher than 9 or even higher than 10 butpreferably not higher than 19 and in particular not higher than 15.Otherwise the resistivity of the mixtures tends to become unacceptablylow for most TN-AMDs, leading to a poor voltage holding ratio. Besidesthis parameter, the media have to exhibit a suitably wide range of thenematic phase, a rather small rotational viscosity and, as mentionedabove, an at least a moderately high specific resistivity.

The displays according to the present invention are preferably addressedby an active matrix (active matrix LCDs, short AMDs), preferably by amatrix of thin film transistors (TFTs). However, the inventive liquidcrystals can also beneficiously be used in displays with other knownaddressing means.

There are various different display modes using composite systems ofliquid crystal materials of low molecular weight together with polymericmaterials such as e.g. polymer dispersed liquid crystal (PDLC)-, nematiccurvilinearily aligned phase (NCAP)- and polymer network (PN)-systems,as disclosed for example in WO 91/05 029 or axially symmetricmicrodomain (ASM) systems and others. In contrast to these, the modesespecially preferred according to the instant invention are using theliquid crystal medium as such, oriented on surfaces. These surfacestypically are pre-treated to achieve uniform alignment of the liquidcrystal material The display modes according to the instant inventionpreferably use an electrical field substantially parallel to thecomposite layer.

LCDs are used for direct view displays, as well as for projection typedisplays.

Liquid crystal compositions with a suitable value of the birefringencefor LCDs and especially for AMD displays are well known. Examples oftechnically advanced compositions for such applications containingcompounds of the formulae

are known e.g. from WO 01/79 379. These compositions, however, do havesignificant drawbacks. Most of them have, amongst other deficiencies,too high values of the birefringence and especially a rotationalviscosity, which is too high and lead to unfavourably long responsetimes.

Thus, there is a significant need for liquid crystalline media withsuitable properties for practical applications such as a wide nematicphase range, appropriate optical anisotropy Δn, according to the displaymode used, an appropriately high Δε, a sufficiently high resistivityand, in particular, a low rotational viscosity.

PRESENT INVENTION

Surprisingly, it now has been found that liquid crystalline media with asuitably high Δε, a suitable phase range, and Δn can be realised, whichdo not exhibit the drawbacks of the materials of the prior art, i.e.which have a significantly lower rotational viscosity compared to mediaof the state of the art having the same clearing point. Thus they allowto realise displays with significantly reduced response times.

These improved liquid crystalline media according to the instantapplication are comprising at least the following components:

-   -   a dielectrically positive component, component A, consisting of        dielectrically positive compounds, preferably comprising one or        more compounds of formula I        wherein    -   R¹ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy        with 1 to 7 C-atoms, or alkenyl, alkenyloxy, alkoxyalkyl or        fluorinated alkenyl with 2 to 7 C-atoms,    -   X¹ is F, Cl or fluorinated alkyl or fluorinated alkoxy, each        with 1 to 4 C-atoms, preferably F or Cl, most preferably F and    -    independently of each other, are        preferably        and preferably    -   Z¹¹ and Z¹² are, independently of each other, —CH₂—CH₂—,        —CF₂—CF₂—, —CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—, —CO—O—, —CH═CH—,        —CF═CF—, —CF═CH—, —CH═CF—, —C≡C— or a single bond, preferably        both are a single bond,    -   L¹¹ and L¹² are, independently of each other, H or F, preferably        L¹¹ is F and most preferably L¹¹ and L¹² both are F,    -   one or more compounds of formula II        wherein    -   R² is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy        with 1 to 7 C-atoms, or alkenyl, alkenyloxy, alkoxyalkyl or        fluorinated alkenyl with 2 to 7 C-atoms, preferably alkyl or        alkenyl,        preferably    -   Z² is —CH₂—CH₂—, —CF₂—CF₂—, —CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—,        —CO—O— or a single bond, preferably a single bond and    -   X² is F, Cl or fluorinated alkyl or fluorinated alkoxy each with        1 to 4 C-atoms, preferably F, OCF₃ or CF₃,    -   optionally one or more compounds, preferably selected from the        group of compounds of formulae of formula III and IV        wherein    -   R³ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy        with 1 to 7 C-atoms, or alkenyl, alkenyloxy, alkoxyalkyl or        fluorinated alkenyl with 2 to 7 C-atoms, preferably alkyl or        alkenyl,        preferably        most preferably    -   Z³¹ and Z³² are, independently of each other, —CH₂—CH₂—,        —CF₂—CF₂—, —CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—, —CO—O— or a        single bond, preferably one of Z³¹ and Z³² is —CO—O— and the        other is a single bond, most preferably Z³¹ is —CO—O— and Z³² is        a single bond,    -   L³¹ and L³² are, independently of each other, H or F, preferably        L³¹ is H and most preferably L³¹ and L³² both are H,        wherein    -   R⁴ is alkyl alkoxy, fluorinated alkyl or fluorinated alkoxy with        1 to 7 C-atoms, or alkenyl, alkenyloxy, alkoxyalkyl or        fluorinated alkenyl with 2 to 7 C-atoms,        most preferably        preferably        most preferably    -   Z⁴¹ and Z⁴² are, independently of each other, —CH₂—CH₂—,        —CF₂—CF₂—, —CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—, —CO—O— or a        single bond, preferably —CO—O— or a single bond,    -   L⁴¹ and L⁴² are, independently of each other, H or F, preferably        L⁴¹ is F and most preferably L⁴¹ and L⁴² both are F,    -   and optionally further dielectrically positive compounds,        -   optionally, preferably obligatorily, a dielectrically            neutral component, component B, consisting of dielectrically            positive compounds, preferably comprising one or more            compounds of formula V            wherein    -   R⁵¹ and R⁵², independently of each other, are alkyl, alkoxy,        fluorinated alkyl or fluorinated alkoxy with 1 to 7 C-atoms, or        alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2        to 7 C-atoms, preferably alkyl or alkenyl,    -   Z⁵ is —CH₂—CH₂—, —CF₂—CF₂—, —CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—,        —CO—O—, —CH═CH—, CF═CF—, —CF═CH—, —CH═CF— or a single bond,        preferably —CF₂—O— or —CH₂—O—, most preferably —CF₂—O—, and    -   n is 0 or 1, and        -   optionally a dielectrically negative component, component C,            consisting of dielectrically negative compounds.

Preferred are liquid crystal compositions comprising in component A oneor more compounds selected from the group of formulae I-1 to I-5

wherein

-   -   R¹, L¹¹ and L¹² have the respective meanings given under formula        I above and    -   L¹³, independently of the other parameters, has the meaning        given for L¹¹ under formula I above, preferably    -   R¹ is n-alkyl with 1 to 7, preferably with 1 to 5 C-atoms,    -   L¹¹, L¹² and L¹³ are, independently of each other, H or F,        generally preferably at least one of L¹¹ to L¹³ is F, most        preferably at least one of L¹¹ and L¹³, most preferably at least        two of L¹¹ to L¹³ are F.

Especially preferred are liquid crystal compositions comprisingcompounds of formula I-1 wherein L¹¹, L¹² and L¹³ are all F and/orcompounds of formula I-2-wherein L¹¹ and L¹² are, independently of eachother, H or F and L¹³ is F and/or compounds of formula I-3 wherein L¹¹and L¹² are H or F, preferably H and L¹³ is F and/or compounds offormula I-4 and/or formula I-5 wherein L¹¹ and L¹² are F and preferablyL¹³ is F.

Especially preferred the compounds of formulae I-1 to I-3 are selectedfrom the respective groups I-1a to I-1d, I-2a to I-2e, I-3a to I-3f, I4ato I4d and I5a to I5d

wherein

-   -   R¹ has the meaning given under formulae I-1 to I-5 above.

Especially preferred are formulations comprising one or more compoundsof formula I-1d and/or one or more compounds of formula I-2b and/or oneor more compounds of formula I-3d and/or one or more compounds offormulae I-4d and/or I-5b.

Preferred are liquid crystal compositions comprising in component A oneor more compounds selected from the group of formulae II-1 and II-2

wherein

-   -   R², X² and        have the respective meanings given under formula IV above and        preferably    -   R² is n-alkyl with 1 to 5 C-atoms,    -   X² is F or OCF₃ and

Especially preferred the compounds of formulae II-1 and II-2 areselected from the respective groups II-1a to II-1d and II-2a and II-2b

wherein

-   -   R² has the meaning given under formulae II-1 and II-2 above.

Preferably component A of the compositions according to the presentinvention comprise one or more compounds of formula II-1a and/or one ormore compounds of formula II-1d, most preferably one or more compoundsof formula II-1d.

Preferred are liquid crystal compositions comprising in component A oneor more compounds selected from the group of formulae III-1 and III-2

wherein

-   -   R³, L³¹, L³² and        have the respective meanings given under formula III above and        preferably    -   R³ is n-alkyl with 1 to 7, preferably 1 to 5 C-atoms, or        1E-alkenyl with 2 to 7, preferably 2 or 3 C-atoms,        preferably    -   L³¹ and L³² both are H.

Especially preferred the compounds of formulae III-1 and III-2 areselected from the respective groups III-1a to III-1h and III-2a toIII-2c

wherein

-   -   R³ has the meaning given under formulae III-1 and III-2 above        and preferably is alkyl.

Especially preferred are liquid crystal formulations comprising one ormore compounds selected from the group of compounds of formulae III-1b,III-2a and III-2b and in particular such formulations comprising one ormore compounds of each of these formulae.

Preferred are liquid crystal compositions comprising in component A oneor more compounds selected from the group of formulae IV-1 to IV-9

wherein

-   -   R⁴, L⁴¹ and L⁴² have the respective meanings given under formula        IV above and    -   L⁴³, independently of the other parameters, has the meaning        given for L⁴¹ under formula IV above, preferably    -   R⁴ is n-alkyl with 1 to 7 C-atoms, or 1E-alkenyl alkenyl with 2        to 7 C-atoms,    -   L⁴¹, L⁴² and L⁴³ are, independently of each other, H or F,        preferably at least one of L⁴¹ to L⁴³ is F, most preferably at        least one of L⁴¹ and L⁴³, most preferably at least two of L⁴¹ to        L⁴³ are F.

Especially preferred the compounds of formulae IV-1 to IV-8 are selectedfrom the respective groups IV-1 a to IV-1c, IV-2a and IV-2b, IV-3a toIV-3d, IV-a and IV-b, IV5-a to IV-5c, IV-6a to IV-6f, IV7a and IV7-b,IV8-a and IV8-b

-   -   R⁴ has the meaning given under formulae IV-1 to IV-8 above and        preferably is alkyl or alkenyl.

Preferably component A comprises one or more compounds selected from thegroup of compounds of formulae IV-1b, IV-1c, IV-2b, IV3-b, IV4-a, IV-3c,IV-4d, IV-5c, IV-6c, IV-6f, IV-7b and IV-8b, most preferably selectedfrom the group of formulae IV-1c, IV-2b, IV-4d, IV-5c and IV-6c.

Preferably the liquid crystal mixtures according to the presentinvention comprise a dielectrically neutral component, component B. Thiscomponent has a dielectric anisotropy in the range from −1.5 to +3.Preferably it consists essentially and especially preferably entirely ofdielectrically neutral compounds. Preferably this component comprisesone ore more dielectrically neutral compounds selected from the group offormulae V-1 to V-3

wherein

-   -   R⁵¹ and R⁵² have the meaning given under formula V above and in        formula V-1 preferably at least one of R⁵¹ and R⁵² is alkenyl,        preferably vinyl or 1E-alkenyl, in formula V-2 preferably R⁵¹ is        alkenyl, preferably vinyl or 1E-alkenyl with 3 or more C-atoms        and R⁵² preferably is alkyl, preferably n-alkyl, preferably        methyl or ethyl and in formula V-3 preferably both R⁵¹ and R⁵²        are, independently of each other, alkyl, preferably n-alkyl.

Further preferred are liquid crystalline media in which thedielectrically positive component, component A comprises one or morecompounds of formula VI

wherein

-   -   R⁶ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy        with 1 to 7 C-atoms, alkenyl, alkenyloxy, alkoxyalkyl or        fluorinated alkenyl with 2 to 7 C-atoms,    -   X⁶ is F, Cl or fluorinated alkyl or fluorinated alkoxy, each        with 1 to 4 C-atoms, preferably F or Cl, most preferably F and    -   m is 0 or 2.    -   wherein, optionally, two of the 6-membered rings may be linked        by a group selected from        -   —CH₂—CH₂—, —CF₂—CF₂—, —CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—,            —CH═CH—, —CF═CF—, —CF═CH—, —CH═CF—, —C≡C——O—, preferably            —CH₂—CH₂— and —CF₂—O—, most preferably —CH₂—CH₂—    -   and from which compounds of formula II are excluded.

In a preferred embodiment the liquid crystal composition comprisescomponent B which one or more compounds of formula VII

wherein

-   -   R⁷¹ and R⁷², independently of each other, have the meaning given        for R¹ under formula I above,    -    independently of each other, and in case    -    is present twice, also these, independently of each other, are    -    preferably at least one of    -    and preferably at least one of    -   Z⁷¹ and Z⁷² are, independently of each other, and in case Z⁷¹ is        present twice, also these independently of each other, —CH₂CH₂—,        —COO—, trans —CH═CH—, trans —CF═CF—, —CH₂O—, —CF₂O— or a single        bond, preferably at least one of them is a single bond and most        preferably all are a single bond and    -   k is 0, 1 or 2, preferably 1 or 2    -   from which compounds of formula V are excluded.

Optionally the liquid crystal mixtures according to the presentinvention comprise a dielectrically negative, component C. Thiscomponent has a dielectric anisotropy of −1.5 or less, and consists ofdielectrically negative compounds having a dielectric anisotropy of −1.5or less. This component C preferably comprises of compounds formula VIII

wherein

-   -   R⁸¹ and R⁸² independently of each other have the meaning given        for R¹ under formula I above,    -    Preferably    -   Z⁸¹ and Z⁸² are, independently of each other, —CH₂CH₂—, —COO—,        trans —CH═CH—, trans —CF═CF—, —CH₂O—, —CF₂O—, —CH₂—O—, —O—CH₂—,        —CH═CH—, —CF═CF—, —CF═CH—, —CH═CF—, —C≡C— or a single bond,        preferably at least one of them is a single bond and most        preferably both are a single bond,    -   L⁸¹ and L⁸² are, independently of each other, ═C(—F)— or ═N—,        preferably at least one of them is ═C(—F)— and most preferably        both of them are ═C(—F)— and    -   i is 0 or 1.

Further preferred are liquid crystalline media in which thedielectrically positive component, component A comprises one or morecompounds of formula IX

wherein

-   -   R⁹ and X⁹ have the respective meanings given for R⁶ and X⁶ under        formula VI above and preferably    -   R⁹ is n-alkyl with 1 to 5 C-atoms and    -   X⁹ is F, Cl, —CF₃ or —OCF₃, most preferably F.

The compounds of formula VI are preferably selected from the group ofsub-formulae VI-1 to VI-18

wherein

-   -   R⁶ and X⁶ have the respective meanings given under formula VI        above and preferably    -   R⁶ is n-alkyl with 1 to 5 C-atoms or alkenyl with 2 to 5 C-atoms        and    -   X⁶ is F, Cl, —CF₃ or —OCF₃, preferably F or Cl and most        preferably F.

Preferably the medium contains compounds of formula VI selected from thegroup of sub-formulae VI-7 to VI-15 and in particular VI-8 and VI-9.

The compounds of formula VII are preferably selected from the group ofsub-formulae VII-1 to VII-10

wherein

-   -   R⁷¹ and R⁷² have the meaning given under Formula VII above.

Most preferably the medium contains compounds of formula VII selectedfrom the group of sub-formulae VII-1, VII-2, VII-4, VII-6, VII-8 andVII-10 and in particular VII-4, VII-6, VII-8 and VII-10.

Especially preferred are the media comprising compounds of formula IXselected from the group of sub-formulae IX-1 to IX-4

wherein

-   -   R⁹ and X⁹ have the respective meanings given under formula IX        above.

Preferably the dielectrically positive component, component A comprisesone or more compounds each of formulae I, II, III and IV and thedielectrically neutral component B comprises one or more compounds offormula V.

Preferably the dielectrically positive component, component Apredominantly and preferably entirely consists of the compoundsmentioned, i.e. of the compounds of formulae I, II, III, IV, VI and IX,preferably of the compounds of formulae I, II, III, and IV, thedielectrically neutral component B predominantly and preferably entirelyconsists of formulae V and VII, preferably of formula V and thedielectrically negative component C predominantly and preferablyentirely consists of compounds formula VIII.

In a preferred embodiment the liquid crystal composition consistspredominantly, preferably entirely of components A and B, preferably ofcomponent A.

The concentration of component A in the formulations according to theinstant invention is preferably in the range from 50% to 100%,preferably in the range from 60% to 97%, whereas in a first preferredembodiment the concentration of component A in the formulations is inthe range from 50% to 75%, preferably in the range from 55% to 75%, in asecond preferred embodiment the concentration of component A in theformulations is in the range from 80% to 100%, preferably in the rangefrom 90% to 98%.

The concentration of component B in the formulations according to theinstant invention is preferably in the range from 0% to 50%, preferablyin the range from 3% to 45%, whereas in the first preferred embodimentreferred to above, the concentration of component B in the formulationsis in the range from 20% to 50%, preferably in the range from 25% to 45%and in particular in the range from 30% to 40%, in the second preferredembodiment referred to above, the concentration of component B in theformulations is in the range from 0% to 20%, preferably in the rangefrom 2% to 16% and in particular in the range from 6% to 19%

The concentration of compounds of formula I in the formulationsaccording to the instant invention is preferably in the range from 3% to30%, preferably in the range from 5% to 20% and in particular in therange from 6% to 19%

The concentration of compounds of formula II in the formulationsaccording to the instant invention is preferably in the range from 1% to25%, preferably in the range from 2% to 20% and in particular in therange from 3% to 15%.

The concentration of compounds of formula III in the formulationsaccording to the instant invention is preferably 10% or more,preferably. 15% or more, more preferably 20% or more and most preferably25% or more. It is preferably in the range from 13% to 45%, morepreferably in the range from 15% to 40% and most preferably in the rangefrom 20% to 35%.

The concentration of compounds of formula IV in the formulationsaccording to the instant invention is preferably in the range from 15%to 60%, more preferably in the range from 20% to 55% and most preferablyin the range from 25% to 50%.

The concentration of compounds of formula V in the formulationsaccording to the instant invention. is preferably in the range from 0%to 50%, more preferably in the range from 2% to 45% and most preferablyin the range from 4% to 40%. Depending on the desired polarity of theformulation the upper limit of the concentration of compounds of formulaV may also be less, preferably 20% or less, more preferably 15 or lessand most preferably 10% or less.

The concentration of the single compounds should be chosen to be not toolarge. Typical upper limits are in the range of 5 to 20% per individualhomologue. The allowable upper limit of the concentration depends on thetype of the compound and on the envisaged application, especially therequirement for the lower temperature limits for operation and storage.Generally, the upper limit of the concentration it is lower forcompounds with four rings than for compounds with three rings and forthese lower than for compounds with two rings. Also generally the upperallowable limit of the concentration is lower for more polar compounds,i.e. for dielectrically neural and for dielectrically positive compoundsthe limit is lower for compounds with a larger dielectric anisotropycompared to compounds with a smaller dielectric anisotropy. Within aseries of homologous compounds the limit typically decreases withincreasing length of the side chain, Obviously there are deviations fromthese rules.

For some of the compounds, which are preferably present in the liquidcrystal formulations according to the present invention, preferred upperlimits of the concentration of the individual homologues have beendetermined.

The concentration of compounds of formula I-1d with R² being an alkylgroup is preferably 11% or less per homologous compound.

The concentration of compounds of formula II-1d with R² being an alkylgroup, preferably a propyl group, is preferably 10% or less andespecially preferred 8% or less per homologous compound.

The concentration of compounds of formula III-1b with R¹ being an ethylgroup is preferably 11% or less, whereas the concentration of compoundsof formula III-1b with R¹ being an n-propyl group is preferably 9% orless.

The concentration of compounds of formula V-3 with R⁵¹ and R⁵²,independently of each other, being an alkyl group is preferably 8% orless and especially preferred 5% or less per homologous compound.

Preferably the liquid crystalline media according to the instantinvention contain a component A comprising, preferably predominantlyconsisting of and most preferably entirely consisting of compoundsselected from the group of formulae I to IV.

Comprising in this application means in the context of compositions thatthe entity referred to, e.g. the medium (the formulation) or thecomponent, contains the component or components or of the compound orcompounds in question, preferably in a total concentration of 10% ormore and most preferably of 20% or more, unless explicitly statedotherwise.

Predominantly consisting, in this context, means that the entityreferred to contains 80% or more, preferably 90% or more and mostpreferably 95% or more of the component or components or of the compoundor compounds in question unless explicitly stated otherwise.

Entirely consisting, in this context, means that the entity referred tocontains 98% or more, preferably 99% or more and most preferably 100.0%of the component or components or of the compound or compounds inquestion unless explicitly stated otherwise.

Preferably component A comprises one or more compounds of formula I,preferably compounds in wherein X¹ is F, preferably of formula I-1 andin particular of formula I-1d.

Preferably component A further comprises one or more compounds offormula II, wherein the ring A² is trans-1,4-cyclohexylene andpreferably X² is CF₃, most preferably of formula II-1 and in particularof formula II-1d.

Preferably component A also comprises one or more compounds of formulaIII, preferably compounds wherein Z³¹ is —CO—O— and/or Z³² is a singlebond and/or L³¹ is F, preferably one or more compounds of formula III-1and/or one or more compounds of formula III-2, especially preferred oneor more compounds of formula III-1e and/or one or more compounds offormula III-2a and/or one or more compounds of formula III-2b.

Also preferably, component A comprises one or more compounds of formulaIV, preferably compounds wherein L⁴¹ is F and/or Z⁴¹ is a single bond ora-CO—O— and/or Z⁴² is a single bond, preferably one or more compounds offormula IV-1 and/or one or more compounds of formula IV-2, and/or one ormore compounds of formula IV-3, especially preferred one or morecompounds of formula IV-1b and/or one or more compounds of formula IV-1cand/or one or more compounds of formula IV-2b and/or one or morecompounds of formula IV-4b.

Preferably, component B comprises one or more compounds of formula V,preferably compounds wherein R⁵¹ and R⁵² are independently of each otheralkyl or alkenyl, preferably n-alkyl including methyl and ethyl or1E-alkenyl including vinyl, preferably one or more compounds of formulaV-1 and/or one or more compounds of formula V-2, and/or one or morecompounds of formula V-3, especially preferred one or more compounds offormula V-1 wherein R⁵¹ and R⁵² are, independently of each other, alkyland/or one or more compounds of formula V-1 wherein R⁵¹ is alkyl and R⁵²is alkenyl and/or one or more compounds of formula V-2 wherein R⁵¹ isalkenyl and R⁵² is alkyl and/or one or more compounds of formula V-3wherein R⁵¹ and R⁵² are, independently of each other, alkyl.

In a preferred embodiment the liquid crystalline media according to theinstant invention contains a component B predominantly consisting of andmost preferably entirely consisting of compounds of formula V.

Especially preferred are media comprising compounds selected from thegroup of formulae VI-8, VI-11 and VI-13 and/or VI-9, VI-12 and VI-15, inparticular with R⁶ being alkenyl, especially vinyl.

In a further preferred embodiment the liquid crystal medium contains aliquid crystal component C, which is preferably predominantly consistingof and most preferably entirely consisting of compounds of formula VIII.

This component C may be present, and preferably is present, besidescomponents A and B.

Also other mesogenic, as well as non-mesogenic, compounds, which are notexplicitly mentioned above, can optionally and beneficiously be used inthe media according to the instant invention. Such compounds are knownto the expert in the field.

Optionally, the inventive media can comprise further liquid crystalcompounds in order to adjust the physical properties. Such compounds areknown to the expert. Their concentration in the media according to theinstant invention is preferably 0% to 30%, more preferably 0% to 20% andmost preferably 0.5% to 15%.

Preferably the liquid crystal medium contains 50% to 100%, morepreferably 70% to 100% and most preferably 80% to 100% and in particular90% to 100% totally of components A, B and C, which contain, preferablypredominantly consist of and most preferably entirely consist of one ormore of compounds of formulae I to and VIII, respectively.

The liquid crystal media according to the instant invention arecharacterized by a clearing point of 66° C. or more, preferably of 70°C. or more and in particular of 75° C. or more. Obviously alsosignificantly higher clearing points can be beneficiously realised.

The Δn of the liquid crystal media according to the instant invention ispreferably in the range from 0.07 to 0.12, preferably in the range of0.075 to 0.115, more preferably in the range of 0.075 to 0.110, mostpreferably in the range of 0.080 to 0.105 and in particular in the rangeof 0.080 to 0.100.

The Δε, at 1 kHz and 20° C., of the liquid crystal media according tothe invention is 6.0 or more, preferably 9.0 or more, most preferably10.0 or more and in particular 11.0 or more. It is, however, preferably17.0 or less, more preferably 15.0 or less and most preferably 12.0 orless.

Preferably the threshold voltage of the liquid crystal media accordingto the invention are in the range from 0.8 V to 1.8 V, more preferablyin range from 0.9 V to 1.7 V, more preferably in range from 0.9 V to 1.6V, and in particular in the range from 1.0 V to 1.3 V or in the rangefrom 1.5 V to 1.6 V, depending on the driver used for the display.

The operating voltages of the liquid crystal media according to theinvention are preferably those of 2.5 V-, 3.3 V-, 4 V- or 5 V-drivers.Particularly preferred are those of 4 V- and 5 V-drivers.

The rotational viscosity of the liquid crystal media according to theinvention are preferably in the range from 50 mPa.s to 200 mPa.s,preferably in the range from 60 mPa.s to 180 mPa.s and in particular inthe range from 70 mPa.s to 140 mPa.s.

For media with a threshold voltage in the range from 1.0 V to 1.3 V therotational viscosity is preferably in the range from 120 mPa.s to, 180mPa.s, whereas for media with a threshold voltage in the range from 1.5Vto 1.6V the rotational viscosity is preferably in the range from 70mPa.s to 130 mPa.s.

Preferably the nematic phase of the inventive media extends at leastfrom 0° C. to 65° C., more preferably at least from −20° C. to 70° C.,most preferably at least from −30° C. to 80° C. and in particular atleast from −40° C. to 80° C., wherein at least means that preferably thelower limit is under cut, wherein the upper limit is surpassed.

In the present application the term dielectrically positive compoundsdescribes compounds with Δε>3.0, dielectrically neutral compounds arecompounds with −1.5≦Δε≦3.0 and dielectrically negative compounds arecompounds with Δε<−1.5. The same definition is used for components. Δεis determined at 1 kHz and 20° C. The dielectric anisotropies of thecompounds is determined from the results of a solution of 10% of theindividual compounds in a nematic host mixture. The capacities of thesetest mixtures are determined both in a cell with homeotropic and withhomogeneous alignment. The cell gap of both types of cells isapproximately 20 μm. The voltage applied is a rectangular wave with afrequency of 1 kHz and a root mean square value typically of 0.5 V to1.0 V, however, it is always selected to be below the capacitivethreshold of the respective test mixture.

For dielectrically positive compounds the mixture ZLI-4792 and fordielectrically neutral, as well as for dielectrically negativecompounds, the mixture ZLI-3086, both of Merck KGaA, Germany are used ashost mixture, respectively. The dielectric permittivities of thecompounds are determined from the change of the respective values of thehost mixture upon addition of the compounds of interest and areextrapolated to a concentration of the compounds of interest of 100%.Components having a nematic phase at the measurement temperature of 20°C. are measured as such, all others are treated like compounds.

The term threshold voltage refers in the instant application to theoptical threshold and is given for 10% relative contrast (V₁₀) and theterm saturation voltage refers to the optical saturation and is givenfor 90% relative contrast (V₉₀) both, if not explicitly statedotherwise. The capacitive threshold voltage (V₀, also calledFreedericksz-threshold V_(Fr)) is only used if explicitly mentioned.

The ranges of parameters given in this application are all including thelimiting values, unless explicitly stated otherwise.

Throughout this application, unless explicitly stated otherwise, allconcentrations are given in mass percent and relate to the respectivecomplete mixture, all temperatures, e.g. the melting point T(C,N), thetransition from the smectic (S) to the nematic (N) phase T(S,N) and theclearing point T (N,I) of the liquid crystals are given in degreescentigrade (Celsius) and all differences of temperatures in degreescentigrade, unless explicitly stated otherwise. All physical propertieshave been and are determined according to “Merck Liquid Crystals,Physical Properties of Liquid Crystals”, Status November 1997, MerckKGaA, Germany and are given for a temperature of 20° C., unlessexplicitly stated otherwise. The optical anisotropy (Δn) is determinedat a wavelength of 589.3 nm. The dielectric anisotropy (Δε) isdetermined at a frequency of 1 kHz. The threshold voltages, as well asall other electro-optical properties have been determined with testcells prepared at Merck KGaA, Germany. The test cells for thedetermination of Δε had a cell gap of 22 μm. The electrode was acircular ITO electrode with an area of 1.13 cm² and a guard ring. Theorientation layers were lecithin for homeotropic orientation (ε∥) andpolyimide AL-1054 from Japan Synthetic Rubber for homogeneuousorientation (ε_(⊥)). The capacities were determined with a frequencyresponse analyser Solatron 1260 using a rectangular wave with a voltageof 0.3 V_(rms). The light used for the electro-optical measurements waswhite light. The set up used was a commercially available equipment ofOtsuka, Japan. The characteristic voltages have been determined underperpendicular observation. The threshold-(V₁₀) mid grey-(V₅₀)- andsaturation voltages (V₉₀) have been determined for 10%, 50% and 90%relative contrast, respectively under perpendicular observation.

The liquid crystal media according to the present invention can containfurther additives and chiral dopants in usual concentrations. The totalconcentration of these further constituents is in the range of 0% to10%, preferably 0.1% to 6%, based on the total mixture. Theconcentrations of the individual compounds used each are preferably inthe range of 0.1% to 3%. The concentration of these and of similaradditives is not taken into consideration for the values and ranges ofthe concentrations of the liquid crystal components and compounds of theliquid crystal media in this application.

The inventive liquid crystal media according to the present inventionconsist of several compounds, preferably of 3 to 30, more preferably of8 to 20 and most preferably of 10 to 18 compounds.

These compounds are mixed in conventional way. As a rule, the requiredamount of the compound used in the smaller amount is dissolved in thecompound used in the greater amount. In case the temperature is abovethe clearing point of the compound used in the higher concentration, itis particularly easy to observe completion of the process ofdissolution. It is, however, also possible to prepare the media by otherconventional ways, e.g. using so called pre-mixtures, which can be e.g.homologous or eutectic mixtures of compounds or using so calledmulti-bottle-systems, the constituents of which are ready to usemixtures themselves.

By addition of suitable additives, the liquid crystal media according tothe instant invention can be modified in such a way, that they areusable in all known types of liquid crystal displays, either using theliquid crystal media as such, like TN-, TN-AM-, IPS- and OCB-LCDs and inparticular in TN-AMDs.

In the present application and especially in the following examples, thestructures of the liquid crystal compounds are represented byabbreviations also called acronyms. The transformation of theabbreviations into the corresponding structures is straight forwardaccording to the following two tables A and B. All groups C_(n)H_(2n+1)and C_(m)H_(2m+1) are straight chain alkyl groups with n respectively mC-atoms. The interpretation of table B is self-evident. Table A liststhe abbreviations for the cores of the structures only. The individualcompounds are denoted by the abbreviation of the core, followed by ahyphen and a code specifying the substituents R¹, R², L¹ and L² asfollows: Code for R¹, R², L¹, L² R¹ R² L¹ L² nm C_(n)H_(2n+1)C_(m)H_(2m+1) H H nOm C_(n)H_(2n+1) OC_(m)H_(2m+1) H H nO.mOC_(n)H_(2n+1) C_(m)H_(2m+1) H H n C_(n)H_(2n+1) CN H H nN.FC_(n)H_(2n+1) CN F H nN.F.F C_(n)H_(2n+1) CN F F nF C_(n)H_(2n+1) F H HnF.F C_(n)H_(2n+1) F F H nF.F.F C_(n)H_(2n+1) F F F nOF OC_(n)H_(2n+1) FH H nCl C_(n)H_(2n+1) Cl H H nCl.F C_(n)H_(2n+1) Cl F H nCl.F.FC_(n)H_(2n+1) Cl F F nCF₃ C_(n)H_(2n+1) CF₃ H H nCF₃.F C_(n)H_(2n+1) CF₃F H nCF₃.F.F C_(n)H_(2n+1) CF₃ F F nOCF₃ C_(n)H_(2n+1) OCF₃ H H nOCF₃.FC_(n)H_(2n+1) OCF₃ F H nOCF₃.F.F C_(n)H_(2n+1) OCF₃ F F nOCF₂C_(n)H_(2n+1) OCHF₂ H H nOCF₂.F C_(n)H_(2n+1) OCHF₂ F H nOCF₂.F.FC_(n)H_(2n+1) OCHF₂ F F nNS C_(n)H_(2n+1) NCS H H nS.F C_(n)H_(2n+1) NCSF H nS.F.F C_(n)H_(2n+1) NCS F F rVsN C_(r)H_(2r+1)—CH═CH—C_(s)H_(2s)—CN H H rEsN C_(r)H_(2r+1)—O—C_(s)H_(2s)— CN H H nAm C_(n)H_(2n+1)COOC_(m)H_(2m+1) H H

TABLE A

PCH

EPCH

BCH

CCP

EBCH

BECH

ECCP

CECP

CEPTP

CCH

D

PDX

ME

HP

EHP

FET

TABLE B

PTP-n[O]mFF

CPTP-n[O]mFF

CB15

C15

CGP-n-X (X = F, Cl, OCF₃ = _(“)OT”)

CGG-n.FX (X = F, Cl, OCF₃ = _(“)OT”)

CGU-n-X (X = F, Cl, OCF₃ = _(“)OT”)

GP-n-X (X = F, Cl, OCF₃ = _(“)OT”)

CDU-n-X (X = F, Cl, OCF₃ = _(“)OT”)

PGP-n-X (X = F, Cl, OCF₃ = _(“)OT”)

PGG-n-X (X = F, Cl, OCF₃ = _(“)OT”)

PGU-n-X (X = F, Cl, OCF₃ = _(“)OT”)

GGP-n-X (X = F, Cl, OCF₃ = _(“)OT”)

PGIGI-n-X (X = F, Cl, OCF₃ = _(“)OT”)

Inm

CBC-nm(F)

ECBC-nm

CCP-V2-m

CCP-nV2-m

CCP-V-m

CCP-nV-m

CCG-V-X (X = F, Cl, OCF₃ = _(“)OT”)

CCG-nV-X (X = F, Cl, OCF₃ = _(“)OT”)

CCP-V2-X (X = F, Cl, OCF₃ = _(“)OT”)

CC-m-V

CC-m-Vn

CCZU-n-X (X = F, Cl, OCF₃ = _(“)OT”)

CGZP-n-X (X = F, Cl, OCF₃ = _(“)OT”)

CCOC-n-m

The liquid crystal media according to the instant invention do containpreferably

-   -   seven or more, preferably eight or more compounds, preferably of        different formulae, selected from the group of compounds of        formulae of tables A and B and/or    -   one, two or more, preferably three or more compounds, preferably        of different formulae, selected from the group of compounds of        formulae of table A and/or    -   two, three, four or more, preferably five or more compounds,        preferably of different formulae, selected from the group of        compounds of formulae of table B.

EXAMPLES

The examples given in the following are illustrating the presentinvention without limiting it in any way.

However, they illustrate typical preferred embodiments. They show theuse of typical and preferred constituents and illustrate theirconcentrations by way of example. Further they show possible variationsof the physical properties of the compositions, illustrating to theexpert which properties can be achieved and in which ranges they can bemodified. Especially the combination of the various properties, whichcan be preferably achieved, is thus well defined for the expert.

Comparative Example 1

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties  1 PCH-7F 9.0 T(N, I) = 70° C.  2 CCH-34 5.0T(S, N) < −40° C.  3 CCH-35 4.0 n_(e) (20° C., 1.5606  4 PCH-301 13.0589.3 nm) =  5 CCP-20CF3 5.0 Δn (20° C., 0.0760  6 CCP-30CF3 5.0 589.3nm) =  7 CCP-40CF3 5.0 ε|| (20° C., 1 kHz) = 9.5  8 ECCP-3F 5.0 Δε (20°C., 6.1  9 BCH-3F.F 7.0 1 kHz) = 10 CCP-2F.F.F 10.0 γ₁ (20° C.) = 94 mPa· s 11 CCP-3F.F.F 13.0 k₁ (20° C.) = 10.5 pN 12 CCP-5F.F.F 6.0 k₃/k₁(20° C.) = 1.25 pN 13 CCZU-2-F 6.0 V₀ (20° C.) = 1.40 V 14 CCZU-3-F 7.0d · Δn = 0.55 μm Σ 100.0 V₁₀ (20° C.) = 1.66 V V₅₀ (20° C.) = 2.00 V V₉₀(20° C.) = 2.43 V

This mixture does not contain any compounds of formulae I and IIaccording to the present invention. It has an unfavourable combinationof the clearing point and rotational viscosity (T(N,I)/γ₁), which leadsto only moderate response times.

Example 1

A liquid crystal mixture according to the present invention is realisedwith the composition and properties given in the following table.Composition Compound No. Abbreviation Conc./% Physical Properties  1CCP-20CF3 4.0 T(N, I) = 74° C.  2 CCP-2F.F.F 7.0 T(S, N) < −40° C.  3CDU-2-F 8.0 n_(e) (20° C., 1.5611  4 CDU-3-F 7.0 589.3 nm) =  5 CCZU-2-F3.0 Δn (20° C., 0.0851  6 CCZU-3-F 15.0 589.3 nm) =  7 PGU-2-F 10.0 ε||(20° C., 1 kHz) = 14.2  8 CGZP-2-OT 8.0 Δε (20° C., 10.0  9 CCG-V-F 3.01 kHz) = 10 CCP-V-1 3.0 γ₁ (20° C.) = 92 mPa · s 11 CC-5-V 12.0 d · Δn =0.50 μm 12 CC-3-V1 12.0 V₁₀ (20° C.) = 1.31 V 13 CCH-35 3.0 14 CCH-3CF33.0 15 CCP- 4.0 20CF3.F Σ 100.0

This mixture has a very favourable value of Δn and an extremely goodcombination of the clearing point and rotational viscosity (T(N,I)/γ₁),which leads to outstanding response times. It has even a slightly lowerrotational viscosity compared to comparative example 1, though itsclearing point is higher and its threshold voltage is lower.

Example 2

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties  1 CCP-20CF3 4.0 T(N, I) = 82° C.  2CCP-30CF3 3.0 T(S, N) < −40° C.  3 CCP-2F.F.F 10.0 n_(e) (20° C., 1.5546 4 CCP-3F.F.F 4.0 589.3 nm) =  5 CCZU-2-F 4.0 Δn (20° C., 0.0808  6CCZU-3-F 13.0 589.3 nm) =  7 CGZP-2-OT 4.0 ε|| (20° C., 10.7  8 CC-5-V16.0 1 kHz) =  9 CC-3-V1 11.0 Δε (20° C., 7.2 10 CCG-V-F 5.0 1 kHz) = 11PGU-2-F 7.0 γ₁ (20° C.) = 91 mPa · s 12 CCH-3CF3 3.0 d · Δn = 0.50 μm 13CCH-35 4.0 V₁₀ (20° C.) = 1.66 V 14 CCP- 4.0 20CF3.F 15 CCP- 4.0 30CF3.F16 CCP- 2.0 50CF3.F 17 CCP-V-1 2.0 Σ 100.0

This mixture has a very favourable value of Δn and an extremely goodcombination of the clearing point and rotational viscosity (T(N,I)/γ₁),which leads to outstanding response times. In particular it has a lowrotational viscosity and an excellent phase range.

Example 3

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties  1 CCP-20CF3 5.0 T(N, I) = 82.1° C.  2CCP-30CF3 4.0 γ₁ (20° C.) = 93 mPa · s  3 CCP-2F.F.F 10.0 d · Δn = 0.50μm  4 CCP-3F.F.F 4.0 V₁₀ (20° C.) = 1.62 V  5 CCZU-2-F 4.0  6 CCZU-3-F10.0  7 CGZP-2-OT 7.5  8 CC-5-V 13.0  9 CC-3-V1 13.0 10 CCG-V-F 7.0 11PGU-2-F 5.5 12 CCH-3CF3 5.0 13 CCH-35 2.0 14 CCP-20CF3.F 3.0 15CCP-30CF3.F 3.0 16 CCP-50CF3.F 4.0 Σ 100.0

This mixture has a very favourable value of Δn and an extremely goodcombination of the clearing point and rotational viscosity (T(N,I)/γ₁),which leads to outstanding response times.

Example 4

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound Conc./ No.Abbreviation % Physical Properties  1 CCP-20CF3 5.0 T(N, I) = 81° C.  2CCP-30CF3 5.0 T(S, N) < −30° C.  3 CCP-2F.F.F 10.5 n_(e) (20° C., 1.5549 4 CCP-3F.F.F 5.0 589.3 nm) =  5 CCZU-2-F 4.0 Δn (20° C., 0.0800  6CCZU-3-F 10.0 589.3 nm) =  7 CGZP-2-OT 5.0 ε|| (20° C., 1 kHz) = 10.2  8CC-5-V 15.0 Δε (20° C., 6.8  9 CC-3-V1 15.0 1 kHz) = 10 CCH-35 3.0 γ₁(20° C.) = 82 mPa · s 11 CCG-V-F 10.0 d · Δn = 0.50 μm 12 PGU-2-F 6.5V₁₀ (20° C.) = 1.68 V 13 CCP-20CF3.F 3.0 14 CCH-3CF3 3.0 Σ 100.0

This mixture has a very favourable value of Δn and an extremely goodcombination of the clearing point and rotational viscosity (T(N,I)/γ₁),which leads to outstanding response times.

Example 5

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound Conc./ No.Abbreviation % Physical Properties  1 CCP-2F.F.F 11.0 T(N, I) = 78° C. 2 CCZU-2-F 3.0 n_(e) (20° C., 1.5529  3 CCZU-3-F 13.0 589.3 nm) =  4CCP-20CF3 5.5 Δn (20° C., 0.0779  5 CCP-30CF3 2.5 589.3 nm) =  6CCP-20CF3.F 1.5 ε|| (20° C., 1 kHz) = 9.5  7 CC-3-V 14.0 Δε (20° C., 6.2 8 CC-3-V1 13.0 1 kHz) =  9 CC-5-V 12.0 γ₁ (20° C.) = 71 mPa · s 10CCH-35 2.0 d · Δn = 0.50 μm 11 CGZP-2-OT 7.5 V₁₀ (20° C.) = 1.71 V 12PGU-2-F 7.0 13 CCG-V-F 3.0 14 CCOC-3-3 1.5 15 CCP-V-1 1.5 16 CCH-3CF32.0 Σ 100.0

This mixture has a very favourable value of Δn and an extremely goodcombination of the clearing point and rotational viscosity (T(N,I)/γ₁),which leads to outstanding response times. In particular it has anextremely low rotational viscosity.

Example 6

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound Conc./ No.Abbreviation % Physical Properties  1 CCH-35 1.5 T(N, I) = 70° C.  2CCP-20CF3 6.0 n_(e) (20° C., 1.5637  3 CCP-30CF3 4.0 589.3 nm) =  4CCP-20CF3.F 9.5 Δn (20° C., 0.0873  5 CCP-2F.F.F 11.5 589.3 nm) =  6CGU-2-F 11.0 ε|| (20° C., 1 kHz) = 15.7  7 CCZU-2-F 4.0 Δε (20° C., 11.1 8 CCZU-3-F 15.0 1 kHz) =  9 CCZU-5-F 5.0 γ₁ (20° C.) = 124 mPa · s 10PGU-2-F 8.0 d · Δn = 0.50 μm 11 CGZP-2-OT 10.0 V₁₀ (20° C.) = 1.11 V 12CCH-3CF3 5.0 13 CC-3-V 7.0 16 CCOC-3-3 2.5 Σ 100.0

This mixture has a favourable value of Δn and a good combination of theclearing point and rotational viscosity (T(N,I)/γ₁), which leads to goodresponse times. It further has a high value of Δε and is suited foroperation with low voltage.

Example 7

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties  1 CCH-35 4.0 T(N, I) = 71.5° C.  2CCP-20CF3 6.0 T(S, N) < −30° C.  3 CCP-30CF3 7.0 n_(e) (20° C., 1.5606 4 CCP-40CF3 4.0 589.3 nm) =  5 CCP-2F.F.F 10.0 Δn (20° C., 0.0864  6CCP-20CF3.F 5.5 589.3 nm) =  7 CGU-2-F 11.0 γ₁ (20° C.) = 131 mPa · s  8CCZU-2-F 5.0 d · Δn = 0.50 μm  9 CCZU-3-F 15.0 V₁₀ (20° C.) = 1.17 V 10CCZU-5-F 5.0 V₅₀ (20° C.) = 1.41 V 11 CC-5-V 3.0 V₉₀ (20° C.) = 1.78 V12 PGU-2-F 6.5 13 CGZP-2-OT 10.0 14 CCH-3CF3 8.0 Σ 100.0

This mixture has a favourable value of Δn and a good combination of theclearing point and rotational viscosity (T(N,I)/γ₁), which leads to goodresponse times. It further has a high value of Δε and is suited foroperation with low voltage.

Example 8

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties  1 CCH-35 5.0 T(N, I) = 70° C.  2 CCH-3CF38.0 T(S, N) < −40° C.  3 CCP-20CF3 8.0 n_(e) (20° C., 1.5602  4CCP-30CF3 8.0 589.3 nm) =  5 CCP-2F.F.F 11.0 Δn (20° C., 0.0863  6CCP-20CF3.F 7.0 589.3 nm) =  7 CGU-2-F 11.0 γ₁ (20° C.) = 133 mPa · s  8CCZU-2-F 5.0 d · Δn = 0.50 μm  9 CCZU-3-F 15.0 V₁₀ (20° C.) = 1.13 V 10CCZU-5-F 5.0 V₅₀ (20° C.) = 1.37 V 11 PGU-2-F 7.0 V₉₀ (20° C.) = 1.74 V12 CGZP-2-OT 10.0 Σ 100.0

This mixture has a favourable value of Δn and a good combination of theclearing point-and rotational viscosity (T(N,I)/γ₁), which leads to goodresponse times. It further has a high value of Δε and is suited foroperation with low voltage.

Example 9

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties  1 CCH-35 5.0 T(N, I) = 70° C.  2 CCH-3CF38.0 T(S, N) < −40 ° C.  3 CCP-20CF3 8.0 n_(e) (20° C., 1.5635  4CCP-30CF3 8.0 589.3 nm) =  5 CCP-2F.F.F 10.0 Δn (20° C., 0.0885  6CCP-20CF3.F 7.0 589.3 nm) =  7 CGU-2-F 11.0 γ₁ (20° C.) = 125 mPa · s  8CCZU-2-F 5.0 d · Δn = 0.50 μm  9 CCZU-3-F 15.0 V₁₀ (20° C.) = 1.13 V 10CCZU-5-F 5.0 V₅₀ (20° C.) = 1.37 V 11 PGU-2-F 8.0 V₉₀ (20° C.) = 1.73 V12 CGZP-2-OT 10.0 Σ 100.0

This mixture has a favourable value of Δn and a good combination of theclearing point and rotational viscosity (T(N,I)/γ₁), which leads to goodresponse times. It further has a high value of Δε and is suited foroperation with low voltage.

Example 10

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties 1 CC-3-V 4.0 T(N, I) = 70.5° C. 2 CCH-3CF38.0 T(S, N) < −30° C. 3 CCP-20CF3 5.0 Δn (20° C., 0.0885 4 CCP-20CF3.F12.0 589.3 nm) = 5 CCP-2F.F.F 11.0 γ₁ (20° C.) = 131 mPa · s 6 CGU-2-F11.0 d · Δn = 0.50 μm 7 PGU-2-F 4.0 V₁₀ (20° C.) = 1.03 V 8 CCZU-2-F 5.09 CCZU-3-F 15.0 10  CCZU-5-F 5.0 11  CGZP-2-OT 11.0 12  CGZP-3-OT 9.0 Σ100.0

This mixture has a favourable value of Δn and a good combination of theclearing point and rotational viscosity (T(N,I)/γ₁).

Example 11

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties 1 CCP-2F.F.F 10.0 T(N, I) = 70.1° C. 2CCP-20CF3 1.0 T(S, N) < −30° C. 3 CGZP-2-OT 15.0 Δn (20° C., 0.1021 4CGZP-3-OT 11.0 589.3 nm) = 5 CCZU-2-F 5.0 γ₁ (20° C.) = 110 mPa · s 6CCZU-3-F 15.0 d · Δn = 0.50 μm 7 CCZU-5-F 3.0 V₁₀ (20° C.) = 1.02 V 8PGU-2-F 9.0 9 PGU-3-F 9.0 10  CC-3-V 15.0 11  CCH-3CF3 7.0 Σ 100.0

This mixture has a favourably high of Δn and a high value of Δε andcompares favourably with the mixture of the following comparativeexample, comparative example 2.

Comparative Example 2

A liquid crystal mixture is realised according to example E of WO01/79379. This mixture has the composition and properties given in thefollowing table. Composition Compound No. Abbreviation Conc./% PhysicalProperties 1 CCP-2F.F.F 10.0 T(N, I) = 69.5° C. 2 CCP-20CF3 4.0 T(S, N)< 40° C. 3 CGZP-2-OT 14.0 Δn (20° C., 0.1052 4 CGZP-3-OT 10.0 589.3 nm)= 5 CCZU-2-F 4.0 γ₁ (20° C.) = 132 mPa · s 6 CCZU-3-F 15.0 d · Δn = 0.50μm 7 CCZU-5-F 3.0 V₁₀ (20° C.) = 0.98 V 8 CGU-2-F 10.0 V₅₀ (20° C.) =1.20 V 9 CGU-3-F 5.9 V₉₀ (20° C.) = 1.50 V 10  PGU-2-F 9.0 11  PGU-3-F9.0 12  CC-3-V 11.0 Σ 100.0

This mixture, which is not using a compound of formula II according tothe present application, has values for the clearing point, Δn and Δεwhich are similar to those of example 11, but it has a significantlylarger rotational viscosity.

Example 12

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties 1 CCH-35 1.5 T(N, I) = 70° C. 2 CCP-20CF36.0 T(S, N) < −40° C. 3 CCP-30CF3 4.0 ε|| (20° C., 15.9 4 CCP-20CF3.F9.5 1 kHz) = 5 CCP-2F.F.F 11.5 εΔ (20° C., 11.1 6 CGU-2-F 11.0 1 kHz) =7 CCZU-2-F 4.0 n_(e) (20° C., 1.5642 8 CCZU-3-F 15.0 589.3 nm) = 9CCZU-5-F 5.0 Δn (20° C., 0.0875 10  PGU-2-F 8.0 589.3 nm) = 11 CGZP-2-OT 10.0 γ₁ (20° C.) = 124 mPa · s 12  CCH-3CF3 5.0 d · Δn = 0.50μm 13  CC-3-V 7.0 V₁₀ (20° C.) = 1.09 V 14  CCOC-3-3 2.5 V₅₀ (20° C.) =1.33 V Σ 100.0 V₉₀ (20° C.) = 1.65 V

This mixture has a favourably high of Δn and a high value of Δε andcompares favourably with the mixture of the following comparativeexample, comparative example 2.

Example 13

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound Conc./ No.Abbreviation % Physical Properties 1 CCP-20CF3 5.0 T(N, I) = 75° C. 2CCP-30CF3 5.0 n_(e) (20° C., 1.5538 3 CCP-2F.F.F 9.0 589.3 nm) = 4CCP-3F.F.F 5.0 Δn (20° C., 0.0802 5 CCZU-2-F 3.0 589.3 nm) = 6 CCZU-3-F12.0 ε|| (20° C., 1 kHz) = 10.7 7 CGZP-2-OT 7.0 εΔ (20° C., 1 kHz) = 7.28 CC-5-V 19.0 γ₁ (20° C.) = 79 mPa · s 9 CC-3-V1 9.0 d · Δn = 0.50 μm10  CCG-V-F 8.0 V₁₀ (20° C.) = 1.45 V 11  PGU-2-F 8.0 V₅₀ (20° C.) =1.82 V 12  CCH-3CF3 7.0 V₉₀ (20° C.) = 2.25 V 13  CCH-35 3.0 Σ 100.0

This mixture has a favourably high of Δn and a high value of Δε andcompares favourably with the mixture of the following comparativeexample, comparative example 2.

Example 14

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties 1 PGU-2-F 8.0 T(N, I) = 70.5° C. 2 CGU-2-F10.0 T(S, N) < −40° C. 3 CGZP-2-OT 11.0 n_(e) (20° C., 1.5669 4CCP-2F.F.F 10.0 589.3 nm) = 5 CCZU-2-F 4.0 Δn (20° C., 0.0865 6 CCZU-3-F9.0 589.3 nm) = 7 CCH-35 4.0 d · Δn = 0.50 μm 8 CC-5-V 18.0 V₁₀ (20° C.)= 1.46 V 9 CC-3-V1 10.0 V₅₀ (20° C.) = 1.75 V 10  CCH-3CF3 6.0 V₉₀ (20°C.) = 2.17 V 11  CCP-V-1 10.0 Σ 100.0

This mixture has a favourably high of Δn and a high value of Δε andcompares favourably with the mixture of the following comparativeexample, comparative example 2.

Example 15

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties 1 PGU-2-F 9.0 T(N, I) = 70° C. 2 CGU-2-F10.0 n_(e) (20° C., 1.5685 3 CGZP-2-OT 11.0 589.3 nm) = 4 CCP-2F.F.F10.0 Δn (20° C., 0.0876 5 CCZU-2-F 4.0 589.3 nm) = 6 CCZU-3-F 9.0 γ₁(20° C.) = 77 mPa · s 7 CCH-35 4.0 d · Δn = 0.50 μm 8 CC-5-V 18.0 V₁₀(20° C.) = 1.44 V 9 CC-3-V1 9.0 V₅₀ (20° C.) = 1.72 V 10  CCH-3CF3 6.0V₉₀ (20° C.) = 2.12 V 11  CCP-V-1 10.0 Σ 100.0

This mixture has a favourably high of Δn and a high value of Δε andcompares favourably with the mixture of the following comparativeexample, comparative example 2.

Example 16

A liquid crystal mixture is realised with the composition and propertiesgiven in the following table. Composition Compound No. AbbreviationConc./% Physical Properties 1 CC-5-V 20.0 T(N, I) = 69.5° C. 2 CC-3-V110.0 n_(e) (20° C., 1.5624 3 CCH-35 4.0 589.3 nm) = 4 PCH-53 5.5 Δn (20°C., 0.0872 5 CCH-3CF3 7.0 589.3 nm) = 6 CGU-2-F 3.5 d · Δn = 0.50 μm 7PGU-2-F 8.0 V₁₀ (20° C.) = 1.50 V 8 PGU-3-F 1.5 V₅₀ (20° C.) = 1.79 V 9CCZU-2-F 4.0 V₉₀ (20° C.) = 2.19 V 10  CCZU-3-F 14.0 11  CGZP-2-OT 11.012  CGZP-3-OT 8.0 13  CCP-30CF3 3.5 Σ 100.0

This mixture has a favourably high of Δn and a high value of Δε andcompares favourably with the mixture of the following comparativeexample, comparative example 2.

1. Liquid crystal medium, characterised in that it comprises adielectrically positive component, component A, consisting ofdielectrically positive compounds, comprising one or more compounds offormula I

wherein R¹ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxywith 1 to 7 C-atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinatedalkenyl with 2 to 7 C-atoms, X¹ is F, Cl or fluorinated alkyl orfluorinated alkoxy, each with 1 to 4 C-atoms,

 independently of each other, are

Z¹¹ and Z¹² are, independently of each other, —CH₂—CH₂—, —CF₂—CF₂—,—CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—, —CO—O—, —CH═CH—, —CF═CF—, —CF═CH—,—CH═CF—, —C≡C— or a single bond, L¹¹ and L¹² are, independently of eachother, H or F, or more compounds of formula II

wherein R² is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxywith 1 to 7 C-atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinatedalkenyl with 2 to 7 C-atoms,

Z² is —CH₂—CH₂—, —CF₂—CF₂—, —CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—, —CO—O—or a single bond and X² is F, Cl or fluorinated alkyl or fluorinatedalkoxy each with 1 to 4 C-atoms.
 2. Liquid crystal medium according toclaim 1, characterised in that it comprises a dielectrically positivecomponent A comprising one or more compounds, selected from the group ofcompounds of formulae III and IV

wherein R³ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxywith 1 to 7 C-atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinatedalkenyl with 2 to 7 C-atoms,

Z³¹ and Z³² are, independently of each other, —CH₂—CH₂—, —CF₂—CF₂—,—CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—, —CO—O— or a single bond, L³¹ and L³²are, independently of each other, H or F,

wherein R⁴ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxywith 1 to 7 C-atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinatedalkenyl with 2 to 7 C-atoms,

Z⁴¹ and Z⁴² are, independently of each other, —CH₂—CH₂—, —CF₂—CF₂—,—CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—, —CO—O— or a single bond, L⁴¹ and L⁴²are, independently of each other, H or F.
 3. Liquid crystal mediumaccording to claim 1, characterised in that it comprises adielectrically neutral component B consisting of dielectrically neutralcompounds and comprising one or more compounds of formula V

wherein R⁵¹ and R⁵², independently of each other, are alkyl, alkoxy,fluorinated alkyl or fluorinated alkoxy with 1 to 7 C-atoms, or alkenyl,alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C-atoms, Z⁵is —CH₂—CH₂—, —CF₂—CF₂—, —CF₂—O—, —O—CF₂—, —CH₂—O—, —O—CH₂—, —CO—O—,—CH═CH—, CF═CF—, —CF═CH—, —CH═CF— or a single bond and n is 0 or
 1. 4.Liquid crystal medium according to claim 1, characterised in that itcomprises a dielectrically neutral component A comprising one or morecompounds of formula III and one or more compounds of formula IV 5.Liquid crystal medium according to claim 1, characterised in that itcomprises a dielectrically negative component C.
 6. Liquid crystalmedium according to claim 1, characterised in that it comprises one ormore compounds of formula I selected from the group of formulae I-1 toI-3

wherein R¹, L¹¹ and L¹² have the respective meanings given in claim 1and L¹³, independently of the other parameters, has the meaning givenfor L¹¹ in claim
 1. 7. Liquid crystal medium according to claim 1,characterised in that it comprises one or more compounds of formula IIselected from the group of formulae II-1 and II-2

wherein R², X² and

have the meanings given in claim
 1. 8. Liquid crystal displaycharacterised in that it comprises a liquid crystal medium according toclaim
 1. 9. Liquid crystal display according to claim 8 characterised inthat it is addressed by an active matrix.
 10. Use of a liquid crystalmedium according to claim 1 in a liquid crystal display.